DC Dan Hart, of British Transport Police, said: “One of the men punched the female victim and then struck the male victim with a glass bottle, causing a cut to his forehead which required stitches.

“This was a violent assault which has left the victim with a nasty head injury. It’s vital that we trace those responsible.”

British Transport Police has issued CCTV images of two men they would like to speak to in connection with the suspected assault.

Anyone with information is asked to contact British Transport Police on 0800 40 50 40, or text 61016, quoting reference MSUB/B6 of 10/10/2014. Information can also be passed anonymously to the independent charity Crimestoppers on 0800 555 111.